00:01
Okay, so let's look at this problem.
00:04
First step, okay, turn it into a matrix.
00:09
Negative 1, 1, 1, and negative 1, 2, negative 3, negative 2, negative 7, negative 2, negative 7.
00:21
Negative 1, 94, 0.
00:26
Okay, so i label this, row 1, row 2, and row 3.
00:31
So the first role operation want to do is we want to use the third row plus three times the first row and we assign this new value to the third row.
00:54
So after this role operation, what we have here is, okay, let's change another color maybe.
01:04
Okay, let's change it to gray.
01:06
Okay, so what we have here is 91, okay, we'll just, okay, we'll just, just copy down the first two rows, because they are unchanged, right? and the third row is negative 0, 1, negative 4, and negative 3.
01:51
Okay, so the next role operation we want to do is we want to turn this to 0.
01:59
So what do we do is we use that second rule.
02:03
Okay, let's label here, row 1, row 2, row 3.
02:06
We use row 2 minus row 1 times 2, sorry, just minus row 1 and we assign this new value to row 2.
02:17
Okay, so now after the operation we have negative 1, 1, 1, 1.
02:23
Okay, copy the first row.
02:26
Okay, the second row is just 0 -1, negative -4, and negative 3.
02:33
And then the third row is 0 -1, 95 -194, negative 3.
02:38
Okay, you can see that these two rows are the, actually the, the same, okay.
02:44
So we can use the third row to subtract the second row, okay? so we assign this value to the third rule.
02:55
Okay, this is row one, row two, and row three.
03:02
We use row three, subtract row two, and then we assign this to row three.
03:08
Okay, so we have zero zero zero, 0, okay.
03:28
And the next step we want to do is we want to use the first role, use the first row and subtract the third rule and we assign this new value to, sorry, the second row, subtract the second row, and then we assign this new value to the first row...